A 26-year-old man was killed Monday evening after a 10-foot-deep tunnel in the sand collapsed on him at Francis Beach in Half Moon Bay, burying him completely, California Department of Forestry and Fire officials said.

The victim, identified by the San Mateo County Coroner’s Office as Adam Jay Pye, of San Lorenzo, had been digging angled tunnels in the sand with friends or family members, said Capt. Jonathan Cox with the Cal Fire Coastside Protection District.

Pye was standing in a 10-foot hole that was angled in the sand when it collapsed on him around 5:28 p.m., completely submerging him, Cox said.

“It is a very rare incident and it’s an incident that obviously goes from being a very hidden danger on the beach to an extreme emergency very quickly because of the dynamics of sand,” Cox said.

Cal Fire crews responded to the scene, along with 30 additional firefighters from throughout San Mateo County who were brought in due to the complexity of the rescue, Cox said.

Crews and an impressive amount of bystanders dug with their hands, buckets and other improvised tools to free Pye and were able to partially expose him within a few minutes, Cox said.

Once his head was surfaced, advanced life support measures were administered, however, Pye remained unconscious, Cox said.

It took crews nearly 35 minutes to completely extract Pye from the sand, Cox said.

“It’s essentially like a trench rescue in the sense that you have material pressing on his body and, until you stabilize the material, it essentially keeps filling back in … so it’s extremely difficult to remove a large amount of sand quickly,” Cox said.

The hole was dug about 10 to 15 feet from the waterline near a campground just north of Kelly Beach, Cox said.

A Life Flight helicopter was dispatched and paramedics tried to revive Pye during the rescue, but he was pronounced dead at the scene, Cox said.

Sand entrapments at beaches are rare and this was one of the first instances that’s occurred in the county, said Paul Keel, San Mateo County park superintendent with the California Department of Parks and Recreation.

“It was a different situation. It creates sympathy for the family, it was a tough incident,” Keel said.

Although it’s not illegal to dig large holes, state park rangers and lifeguards frequently make safety contacts on the beach, Keel said. Officials will advise visitors to stop engaging in dangerous activities or from doing things that are disruptive to the environment, Keel said.

Firefighters are also reminding residents to be aware of hidden dangers at the beach. People should stay back from cliffs, use caution when swimming in big surf and not dig too deeply in the sand, Cox said.